Before your next youth meeting, arrange 5 or 10 things in the room in an unusual and incorrect way. If you want to get totally crazy here, hang the window blinds upside down, flip over a computer monitor - flip the tv onto its side- and have movies playing when they come in, -- be inventive; Put your shirt on backwards or inside out, etc.
Have each of the teens pair up and then challenge them to find all the things working in the youth room.